Those trying to do it today may not be able to because the feature is 'erroring' out with a 500 error response code.

Jade, the Google+ Local community manager said in a Google Places Help thread that they are aware of the issue. She wrote:

Seeing reports of users getting 500 errors when attempting to verify their social local Google+ page. The team's aware and working on it. I'll post back on this thread with updates.

You can help by:
- Sending feedback from your profile or page. Either from the gray Send feedback text on the bottom of the right column on your page, or, from the gear icon.
- Posting links to the pages you are trying to verify here.